1. Field of the Invention
This invention relates generally to wind turbines and windmills, and more particularly to a vertical axis wind machine having apertures and flaps.
2. Description of Related Art
Wind machines such as windmills and wind turbines have been made and used over the centuries to utilize the naturally occurring power of the wind for tasks such as grinding grain, pumping water, and, more recently, for generating electricity. Wind machines fall in two primary classes horizontal axis machines and vertical axis machines. The first instance of a wind powered machine was probably a windwheel operating an organ by Hero of Alexandria in the 1st century AD. Vertical axis wind machines were first used in eastern Persia by the 9th century AD. Several centuries later, in the 1180s, horizontal axis windmills were invented and used in northwestern Europe.
The orientation of a wind machine to capture maximum wind energy has profound implications with horizontal axis wind machines having vertical blades. The need to orient a horizontal axis wind machine to capture maximum wind energy has led to moveable mechanical components, as well as, in recent history, electronic controls. These components add tremendously to the efficiency of a horizontal axis wind machine, but also increase cost and maintenance. In addition, a horizontal axis wind machine has both a startup wind speed and a maximum wind speed. This often times leads to the unfortunate consequence that the wind machine cannot operate during times of peak wind energy. In addition, operation of many horizontal axis wind machines in high wind speeds will damage or destroy the wind machine. This problem is not as prevalent with vertical axis wind machines due to the inherent drag that is created when a blade on a vertical axis machine rotates against the direction of the wind. This drag slows the rotational speed of a vertical axis machine, and also lowers its efficiency. Nonetheless, vertical axis wind machines are still desirable due to their simplicity and lower cost. There are no complicated mechanical or electrical controls required to steer the wind machine into an orientation that achieves maximum efficiencies. The slower rotational speed and lower efficiencies of vertical axis wind machines are shortcomings that limit their widespread use, and make vertical axis wind machines undesirable for electricity generation where higher rotational speeds are required. The present invention, as described by way of this specification and the attached drawings, overcomes the shortcomings of vertical axis wind machines.
It is therefore an object of the present invention to provide a vertical axis wind machine that has improved efficiencies. It is another object of the present invention to provide a vertical axis wind machine that has lower return drag. It is yet another object of the present invention to provide a vertical axis wind machine that has improved torque characteristics. It is yet another object of the present invention to provide a vertical axis wind machine that has lower operating noise. It is still another object of the present invention to provide a vertical axis wind machine that does not require feathering controls in high wind conditions. It is another object of the present invention to provide a vertical axis wind machine that is independent of wind direction and has fewer moving parts.